just went through your stuff.. I think your style is one of my favorites here on Newgrounds. Colors are good, anatomy is damn near perfect, and overall finish looks great while still retaining that slightly sketchy feel that i so love. Mancrush, right there.
If I were to suggest anything, it would be to try for more ambitious pieces - awesome as your art is, i kinda feel you're limiting yourself (this is speaking about your portal submissions so far; the image you posted here is a good example of what you could/should be doing in terms of composition)..
Yeah that about covers it. Cheers man, keep at it.